Qual-Craft Industries 2481 The Guardian, Fall Protection Ladder Hook With Wheel, Provides Ideal Method Of Securing The Top Of A Ladder To A Rooftop, When Used With A Paired Ladder Hook, Both Hooks Fit Over The Top 2 Rungs Of The Ladder & Hook Over The Roof Edge, Wing Nuts Of Both Hooks Are Tightened Holding The Ladder Firmly In Place, Designed To Fit Single Or Extension Ladders, Made From Powder Coated Steel For Superior Durability & Strength.